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Type: Journal article
Title: Electromagnetic structure of decuplet baryons towards the chiral regime
Author: Boinepalli, S.
Leinweber, D.
Moran, P.
Williams, A.
Zanotti, J.
Zhang, J.
Citation: Physical Review. D. Particles, Fields, Gravitation and Cosmology, 2009; 80(5):1-26
Publisher: American Physical Soc
Issue Date: 2009
ISSN: 1550-7998
Statement of
S. Boinepalli, D. B. Leinweber, P. J. Moran, A. G. Williams, J. M. Zanotti, and J. B. Zhang
Abstract: The electromagnetic properties of the baryon decuplet are calculated in quenched QCD on a 203×40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover fermion action with quark masses providing a pion mass as low as 300 MeV. Magnetic moments and charge radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. We present results for the higher-order moments of the spin-3/2 baryons, including the electric-quadrupole moment E2 and the magnetic-octupole moment M3. The world’s first determination of a nonzero M3 form factor for the Δ baryon is presented. With these results we provide a conclusive analysis which shows that decuplet baryons are deformed. We compare the decuplet-baryon results from a similar lattice calculation of the octet baryons. We establish that the environment sensitivity is far less pronounced for the decuplet baryons compared to the octet baryons. A surprising result is that the charge radii of the decuplet baryons are generally smaller than those of the octet baryons. The magnetic moment of the Δ+ reveals a turnover in the low quark-mass region, making it smaller than the proton magnetic moment. These results are consistent with the expectations of quenched chiral perturbation theory. A similar turnover is also noticed in the magnetic moment of the Σ*0, but not for Ξ* where only kaon loops can appear in quenched QCD. The electric-quadrupole moment of the Ω- baryon is positive when the negative charge factor is included, and is equal to 0.86±0.12×10-2  fm2, indicating an oblate shape.
Rights: ©2009 American Physical Society
RMID: 0020092802
DOI: 10.1103/PhysRevD.80.054505
Appears in Collections:Physics publications

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